Traditional phase separation devices, such as tubal, decanter and cone centrifuges have been used for various separation tasks, including those in medicine and pharmaceutical production, and wastewater treatment. Selection of the type of separation devices has depended upon such factors as residence time desired, size of waste particles, G force required to effect separation, and tolerances for such factors as interrupted use to clean system, noise, vibration, wear, energy use and maintenance.
More recently, U.S. Pat. No. 6,312,610 disclosed a density screening device employing a thick-shelled outer cylinder wall having a series of indentations, each of which leads to a nozzle or opening that penetrates the outer wall of the outer cylinder. Through the openings, the continuous, non-mechanically assisted accumulation and ejection of heavy particle waste occurs along the entirety of the centrifugal device. The waste is collected by an exterior, non-rotating catchment cylinder or similar device in which the outer cylinder resides and rotates. The heavier waste materials accumulate on the stationary catchment cylinder wall and merely drip downwards at normal earth gravity, without further opportunity for recovery.